Spiral: From the Book of Saw

During a Fourth of July parade, off-duty Detective Marv Bozwick chases a thief down a sewer drain pipe. Attacked from behind by a figure wearing a pig mask, Bozwick awakens to find himself suspended by his tongue in an active subway tunnel and is given a choice via recorded message: tear out his tongue and live, or remain until the next train arrives, killing him. Unable to escape the trap in time, Bozwick is hit by the train and killed. The next day, police Captain Angie Garza assigns Detective Zeke Banks a new partner, idealistic rookie William Schenk. Zeke and Schenk investigate Bozwick's death and Zeke recognizes the elaborate trap as the modus operandi of the now deceased Jigsaw Killer. Meanwhile, homicide detective Fitch – who several years prior had ignored a backup call from Zeke, resulting in Zeke nearly getting killed – is abducted and placed in a trap where he must allow a device to rip his fingers off to avoid electrocution in a filling water basin; he also fails to escape and dies. Some officers begin to suspect that Zeke may be responsible, due to his history with Fitch. A box then arrives at the station, containing a pig puppet and a piece of Schenk's tattooed skin inside. A small vial inside the box directs the police to a butcher shop, which was previously a hobby shop that Zeke and his father, retired chief Marcus Banks, used to visit. Upon arriving, the team discovers a tape recorder and a skinned corpse, identified as Schenk. Deciding to track down the killer himself, Marcus travels to a warehouse, where he is abducted. Shortly afterwards, Garza is kidnapped, and placed in a trap in the precinct's cold storage where she has to sever her spinal cord on a blade to stop boiling wax flowing from a pipe onto her face. She fails to do so and dies from her injuries, moments before Zeke discovers her body. While chasing a lead, Zeke is captured and wakes up at the warehouse, handcuffed to a pipe with a hacksaw nearby. He considers sawing off his arm, but successfully escapes using a loose bobby pin. He then discovers his former partner Peter Dunleavy, who was imprisoned when Zeke exposed a murder he committed, chained in place. In front of him is a large glass-crushing machine, which has been modified to hurl shrapnel at him. A tape recorder explains that Zeke can choose to either free him or leave him to die. Although Zeke attempts to save Dunleavy, he cannot get the key in time. Moving to another room, Zeke then finds Schenk, who is revealed to have faked his own death by using the skinned corpse of the thief who lured Bozwick into the tunnels, and has been the copycat all along. He explains that his last name is actually Emmerson, the son of Charlie Emmerson, who was the man Dunleavy killed because he had agreed to testify against a dirty cop. He also reveals that Marcus, during his time as chief, deliberately protected corrupt officers to "clean" the streets of crime more efficiently under Article 8. Believing that Zeke can be an ally, Schenk presents him with a final test, revealing Marcus suspended above the floor and slowly being drained of blood. Schenk calls 9-1-1 and claims that he is a civilian being pursued by a shooter, resulting in the dispatch of a SWAT team. He hands Zeke a revolver with one cartridge, and offers him the choice to either shoot a target that will save Marcus but allow Schenk to escape, or to kill Schenk and let Marcus bleed to death. Zeke shoots the target to save his father, causing his restraints to loosen and lowering him to the ground, and then begins to fight Schenk. The SWAT team arrives and inadvertently triggers a tripwire, causing Marcus' restraints to yank him upward again. The movement reveals a gun affixed to Marcus' arm, leading the SWAT team to mistake him for the shooter and kill him. Zeke screams in despair as Schenk escapes.